Serological diagnostic tests for COVID-19

Abstract

Introduction: The correct diagnosis of a patient with suspected COVID-19 is a critical step for appropriate clinical management. Although RT-PCR still remains the gold standard for COVID-19 diagnosis, serological tests are becoming an important resource considering their availability, feasibility and timeliness of results.

Objective: To analyse the characteristics, limitations, indications and the interpretation of serological tests available in Brazil for COVID-19 diagnosis.

Methods: A literature review on PubMed searching the terms “SARS-CoV-2”, “COVID-19”, “serological tests” and data given by Brazilian Ministry of Health correlating those data to known concepts of epidemiology.

Results: There are many serological methods to identify antibodies. In Brazil, more than 60 tests are available. Most of these are serological rapid tests based on immunochromatography. Tests that detect antibodies against nucleocapsid tend to have higher sensitivity, meanwhile, tests that identify antibodies against the spike protein are more likely to have a higher specificity. There available tests that identify both of these antibodies having a very high standard both for sensitivity or specificity.

Conclusion: Serological tests for SARS-CoV-2 can be useful if properly indicated and interpreted. It is necessary to understand their different characteristics and inherent limitations. Proper interpretation of its results also requires knowledge of local prevalence of the disease and date of symptom onset 

Keywords: SARS-CoV-2; COVID-19; serological tests; accuracy